this could happen if TC2 was already 0 when it was started or reset
resulting in the initial reset not happening until TC0 had overflowed for
the first time as the delay to ensure this didn't happen would be missed
when TC2 was already 0
the new behaviour results in TIOA0 being toggled when a software trigger
of TC0 happens which makes TC2 reset immediately without having to wait
for TC0 to overflow
* Add `.ramfunc` section to bootrom loader script
* exclude spiffs functionality from flashmem.h/flashmem.c
(allows bootrom to use flashmem)
* hide unused tick.h / flashmem.h functions from bootrom
(not technically necessary; see comments)
* bootrom: add source files, include path, and defines when
`PLATFORM_DEFS` defines `WITH_FLASH`
* Define `AS_BOOTROM` to indicate code is building for bootrom
